Electrolytic cell



Dag. 27, 1927.

' 1,653,879 H. o. slEGMuND ELEGTROLYTIC CELL Filed Oct. '22. 1924 In vemor Humphreys 0.5/'egmund by Affgy Patented Dec. 27, 1927.

UNITED ASTATES g rss-3,79 PATENT OFFICE..

HUMPHREYS 0. SIEGMUND, OF WEST ORANGE, NEW JERSEY, ASSIG-N'OR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YOIRIK.A

ELECTROLYTIC CELL.

Application led October 22, 1924. Serial No. 745,049.

' This invention relates to electrolytic cells and has'for an object the provision of a supporting member' for mechanically weak electrodes.

The invention has particular application to a metallic support for tin cathodes in electrolytic cells, though it is not limited to this application alone.

It is commonly known that in electrolytic condensers the electrode members should be composed of some metallic composition which is substantially inert to the destructive chemical action of the electrolyte employed. The anodes in such pieces of appa- 15 ratus are usually composed of some, {ilmforming metal, such as aluminum, for example. When used across circuits of unidirectional and pulsating potential, the cathode members of such cells should be composed of 2o a composition which, when the current density on the cathode surface is high, is not only inert to the action of the electrolyte, but which is also a non-film forming material. For this purpose tin has been found to be satisfactory. Because of the non-rigid character of tin, however, it has been found desirable, in accordance with the invention, to mechanically strengthen electrodes composed of tin by supporting them in the cell with elements having a rigid character,

From a mechanical viewpoint metals, of course, form the most desirable material for use as supporting elements. It isknown,

however, that when a mechanical joint between metallic elements is immersed in an electrolyte, a corrosion of the metals is likely to result. In time, this corrosion may reach such a depth that the metals become consumed at the joints. Furthermore, this corrosion has been found to increase the watt loss by increasing the resistance of the joints.

One cause of such corrosion has been found to be the local or galvanic action` which is characteristic in joints between metals. This galvanc action has in turn been found to be due to the difference between the absolute potentials of the metals and it is generally believed that the corrosion or galvanic action varies directly with this difference between the absolute potentials. Thus, between elements which are near together in the so-called electro-motive series of elements-an arrangement of elements in accordance with their absolute potentialsbetween those metals which are f ar apart.

It has been found, however, thateven the small reverse current set up between metals close together in the electro-motive series rsults in an undesirable corrosion when employed in electrolytic condensers.

Further, any metal used as a supporting element for catho-de members in electrolytic condensers should be substantially unattacked by the electrolyte employed. The invention provides, therefore, a method for and means of joining a wide range of metals, without thepresence of the undesirable corrosion or galvanic action described above.

A fuller understanding of the invention will be obtained from the more detailed description to follow. l

In the accompanying drawings in which similar parts are indicated in the several figures by the same reference characters, Fig. 1 isa side view, along the line 1-1 of Fig. 3, of a cell employing the supports of this invention. Fig. 2 is an end sectional view, along the line 2--2 of Fig. 1. Fig. 3 is a top view, along the line 3-3 of Fig. 2.

An electrolyte 4 is contained in an insulating casing 5 over which a cover 6 is fitted. Anodes 7 composed of a film forming composition, aluminum, for example, areV suspended from a cover and between suitable cathodes 8, such as tin, for example. The cathodes are supported in accordance with this invention by supporting members 9 suspended from the cover and composed of a film-forming composition which is electro-positive to the composition of the cathode, such as aluminum, for example. The cathodes may be mechanically joined to the supports by rivetslO which mayl also be composed of the composition forming the support. The use of mechanical joints has been found to `be more satisfactory than welded or soldered joints in that harmful impurities in the form of fluxes are not thus introduced into the electrolyte.

It has been found that the usual corrosion existing in metallic joints is substantially eliminated when hlm-forming metals are joined to metals which are electro-negative to them; for example, aluminum, as a filmforming metal, may be joined without corrosion to tin, which is electro-negative to it.

"cell, such as that formed,

This elimination of corrosion in joints between film-forming metals and metals electro-negative to them is believed to be due to the dielectric film formed on the film- 'forming metal when it is an anode' in any for example, when .it 1s joined in an electrolyte to-metal electro-negative to it. It is known lthat` this ilm intime becomes heavy enough to appreciably retard the iw of a current from the\\flmforming metal into the electrolyte although not appreciably affecting the flow of current from the electrolyte to the lmforming metal. Such a film would, therefore, hinder any tendency for a current to flow from aluminum, for example, to metal electro-negative to it in a joint composed of the two metals; and would, therefore, retard corrosion in such a joint. Actual practice h as shown that such supports constitute a satisfactory and practical means of supporting mechanically Weak electrodes which are electro-negative to the supports, extended tests over periods of many months having been made with no signs of corrosion at the joint of electrode and electrode support.

and

Any lilmforming composition such as tantalum or magnesium, for example, is, of course, suitable for use to eliminate corrosion in joints and it will, therefore, be appreciated that the invention is not to be restricted to the use of aluminum.

While the invention has been illustrated specicall in connection with supports for tm catho es in electrolytic cathodes, it will be appreciated that it is not intended to impose any restrictions upon the application of the invention other than those set forth in the claims, but that the invention may be employed to eliminate corrosion in a Wide range of joints.l

What is claimed is: v

In an electrolytic condenser, a casing, a lm forming electrolyte within said casln tin electrodes immersed in said electro] means :for supporting said electrodes, said means comprising aluminum supports. Y In Wit-ness whereof, I hereunto subscribe my name this 15th day of October, A. D. 1924.

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HUMPHREYS O. SIEGMUND. 

